The present invention relates to a multi-chip module and a process for manufacturing it.
The multi-chip module is one for constructing a desired system by preparing an integrated circuit such as a CPU, a RAM, a ROM or a gate array as the unit of semiconductor chip and by packaging the chips over a wiring substrate. The method used for packaging the semiconductor chips over the substrate is exemplified by the wire bonding, TAB or flip chip method. On the other hand, the material used for the wiring substrate is exemplified by ceramics, synthetic resins or silicon wafers.
One example of the multi-chip module is described on pp. 185 to 194 of IEEE TRANSACTIONS ON COMPONENTS, HYBRIDS, AND MANUFACTURING TECHNOLOGY, VOL.12, NO.2, JUNE 1989. In this publication, there is proposed a structure for wiring the semiconductor chips and the substrate by forming the main surface of a silicon wafer with holes having a size approximately equal to that of the semiconductor chips and by patterning the wires between the semiconductor chips buried in the holes and the substrate. The wires are formed by forming the main surfaces of the semiconductor chips with wire connecting pads, by burying the semiconductor chips in the holes and by depositing a conductive film of Al or the like on the main surface of the substrate. Next, the wires are patterned by applying a photoresist to the conductive film, by subjecting the photoresist to an exposure with a wiring photo mask and then to a development, and by etching the conductive film with the resist mask obtained.